Tahoe Backcountry Snow

0410 wx. at 6350′ in Carnelian Bay: 31.8° / 17.4° dew point / 54% RH

0515 wx. at 8400′ Mt. Rose backcountry TH: 31° / mostly clear skies / light SW winds with moderate gusts

0630 wx. at 9500′: 28.7° / -11.8° dew point / 16.8% RH / clear skies / SW winds at 8 mph, gusting to 14 mph.

Backcountry obs.:

Hard. Scratchy. Slippy. Loud. Hateful. Any of the aforementioned adjectives can be used alone or together to accurately describe both the skin up and descent conditions currently found in the backcountry. Cold snow that persisted in the higher elevations over the weekend is largely gone, cooked into melt/freeze surfaces across the majority of elevations and aspects.

Stout, supportable melt-freeze surfaces exist on E-S-NW aspects at all elevations. In sheltered N and NE zones below treeline, a 1/4 to 1/2″ non-supportable crust tops remnant soft snow. The breakable crust offers a slight reprieve from edge slipping and backsliding now common in skintracks. Minimize misery; bring ski crampons.

Heavy usage from the past two weekends, especially during warm periods, has left the snowpack tracked and rutted in popular zones, providing rough, chattery dawn descents.

Warm temps. continuing throughout the workweek should quickly soften snow surfaces each morning, providing buttery corn turns if timed just right in the late morning/early afternoon.

Weather and forecast thoughts:

Well-above average, spring-like temps will continue throughout the work week under mostly clear skies. Highs through Fri (2/28) will reach the middle to upper 40s above 7000′, with lows dipping to near or just below freezing each night. A generally dry airmass will also aid in nightly surface refreezes through evaporational cooling.

While cold mornings make for hard, leg-pounding dawn patrol laps, this spring pattern does create prime conditions for an early season corn harvest for those that can time the snow just right.

Looking ahead, winter is plotting a return around the beginning of March. Forecast ensembles show a return to a colder, more active pattern starting this coming weekend (3/1-3/2). A modest system could begin impacting the area by late Sat (3/1), bringing good chances for snow showers and light accumulations into Sun and possibly Mon (3/2-3/3). Temps will cool with the new pattern, bringing snow levels below 7000′. Precip. amounts look light and variable at this time, but a surface refresh from the first system isn’t out of the question.

Looking ahead to later in the week, there are hints for increasingly impactful systems with the potential to drop more significant amounts of snow. Additionally, the upper level flow appears to continue steering storms into the Sierra into the second week of the month.

0430 wx. at 6350′ in Carnelian Bay: 25.9 deg. / 19.6 deg. dew point / 77% RH / calm winds and clear skies

0530 wx. at 8650′ Mt. Rose TH: 20 deg. / calm winds / clear skies

0630 wx. at 9900′ in Mt. Rose backcountry: 24.0 deg. / 11.6 deg. dew point / NE winds at 5mph / high broken overcast skies

Backcountry obs.:

The Mt. Rose backcountry hosted cold, powdery surface snow this morning (2/21) with 2-4″ of light, low density snow atop a springy base. Temps in the low to mid 20s and moderate NE winds throughout the day yesterday (2/20) kept snow surfaces frozen, despite mostly sunny skies. Sun crust was limited to aspects receiving the most intense solar exposure during the day yesterday (SE-S-SW).

Near and above treeline, N and NE aspects showed little wind effect, skiing fast, soft, and super fun. Whoops and giggles from surprised skiers crackled through the early morning silence, signaling yet another sneaker pow morning.

Weather and forecast thoughts:

Not much change to the forecast from yesterday. Starting today, a warmup overtakes the region lasting through the end of February, bringing the season’s first substantial corn skiing window.

Highs in the backcountry will warm into the 40s this weekend under mostly sunny skies. Lows this weekend will be in the upper 20s and 30s above 8000′, providing generally good overnight refreezes. Sunday (2/23) increased breezes and high clouds will signal the passage of a weak system to our north. A few light showers are possible Sun. evening into early Mon. Snow levels for any precip. that does fall will be above 8000′.

The coming work week will be dry and mild with highs in the 40s above 8000′ and lows in the upper 20s to lower 30s. Snow surfaces should receive decent overnight refreezes through radiational cooling. This should set the stage for a prolonged window of early spring corn.

Models suggest modest, colder systems entering the picture around the ides of March continuing into the first full week of the month. Winter’s not over yet.

0700 wx. at 6350′ in Carnelian Bay: 22.8 deg. / 21.0 deg. dew point /93% RH. / Clear skies / 1″ new snow overnight

Backcountry obs., Eastside edition:

I spent the past weekend (2/14-2/17) in the Eastern Sierra checking out the newly refreshed snowpack near Convict Lake, Rock Creek, and Lee Vining. While there is now a useable snowpack in all three areas for the first time this season, signs of active instability were widespread, limiting access to low consequence terrain. Across the region, the recent storm dropped anywhere from 2-4′ of new snow above 7500′. In areas below 8000′, much of this fell on bare ground, sage and shrubs, and in some areas, faceted snow. Highest storm totals were from Mammoth north, with amounts tapering to the south. The storm snow exhibited an upside down character with multiple inches of lighter density snow, beneath a foot or more of denser snow near the surface.

Skinning near Convict Lake, the snow had a trampoline-like feel underfoot, with the denser surface snow bonded together atop cold, unconsolidated snow intermixed with shrub branches beneath. Near and above treeline, wind slabs felt drummy and hollow. On larger bowls, chutes, and prime avalanche terrain, evidence of recent large avalanches abounded. Numerous N and E facing chutes and bowls were dotted with visible crowns up high, and debris piles at their bases.

Adding to the awkward and unsettled feel of the snowpack was warmth. By 2:30pm on Sat., temps. climbed to 32.9 deg. at 10,780′ on Mt. Aggie. Snow quickly warmed and what had just been fluffy powder, quickly turned to hot pow and mashed potatoes. Increasing afternoon breezes refroze the snow surface in open areas so that a new, stiff and breakable crust now topped the newly heated, mashed potatoes underneath: mama’s secret recipe.

Saturday’s warmup was region-wide so that by Sun am, all but the most sheltered N and NE aspects in Rock Creek above 9000′ hosted 1″ thick melt-freeze crust atop 2-3′ of warming soft snow. Trail breaking was strenuous with deep ski penetration and constant skin glopping. Surprisingly, by mid afternoon the snow had warmed enough to weaken the previously breakable crusts. The skiing ended up being far more fun and enjoyable, especially down low, than anticipated. A few thousand feet of fun and giggly hot-pow replaced earlier fears of an afternoon combating death crust.

Late Sun and Mon (2/26-17), more changes arrived as a system to the north increased winds dramatically over the higher peaks, sending plumes and banners of fresh snow skyward and onto leeward slopes. On Mon (2/17) fresh wind slab avalanche debris littered the bases of bowls and couloirs in the alpine above Lee Vining. Touring on sheltered N and NE aspects of Mt. Dana, revealed surfaces of thick melt-freeze crust atop upside-down hot pow. Above treeline, wind sculpted sastrugi, edgeable windboard, breakable crust, and powerful SW winds all conspired to turn casual touring into a heads up adventure.

The Eastside now has a snowpack, it just needs time to settle and stabilize. With luck, a few more dumps in the next month will add more depth and set the stage for the sunny, good timing days of High Sierra spring.

Weather and forecast thoughts:

Speaking of spring, aside from the weak system affecting the area yesterday, warmth, sunshine, and high pressure will be the themes for the next week and beyond heading into March. Goodbye winter powder, hello spring corn.

The recent warmth earlier this week (2/17-2/19) that largely cooked the backcountry snowpack, departed late yesterday (2/19) with a weak storm, leaving a dusting of snow atop freshly frozen crusts. Today highs will remain cool in the lower 30s above 7000′ under sunny skies with some light N and NE breezes.

Starting on Fri (2/21) through the weekend and into next week, temps in the backcountry will warm into the 40s each afternoon under mainly sunny skies. Some passing storms in the Pac NW may bring periods of high clouds on Sun (2/23). However, that won’t keep temps. from rising each afternoon into the middle and upper 40s. Some locations could even flirt with 50 degrees early next week.

Nights for the coming period will be generally clear, permitting efficient radiative cooling of the snowpack. Lows in the backcountry will fall to the 20s and low 30s in a drier airmass, promoting additional cooling of snow surfaces. Nightly inversions are likely as well.

The coming combination of warm, sunny days and cold clear nights should combine to produce the first good corn cycle of the season this weekend through the end of the month.

Will winter return? Model ensembles suggest a pattern change back to unsettled weather possible around the first week in March.